Vehicles include security systems to prevent unauthorized ignition of the vehicle engine. The most common type of security system is an ignition lock defining a slot to receive a key. The ignition lock will not turn unless the key is inserted in the slot and the vehicle will not start unless the ignition lock is turned. A more complicated security system includes a key recognition system in which the vehicle's key includes a transponder that communicates with a sensor in the vehicle. Each key is uniquely identifiable and unless the proper key is inserted in the ignition lock the vehicle will not start. Generally, the transponder associated with the key requires a magnetic field to communicate with the sensor and so a coil encircles the ignition lock to carry an electric current and generate a magnetic field.